SARS‐CoV‐2 infection after August 2022 in Dutch blood donors without serological signs of prior infection

Background and Objectives After several years of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) circulation in the Netherlands, most individuals acquired the infection. However, an unknown number of uninfected persons could still be solely dependent on vaccination for protection. In this study, we aimed to retrospectively quantify the proportion of blood donors, without signs of prior SARS‐CoV‐2 infection, who acquired SARS‐CoV‐2 infection after August 2022. Materials and Methods Based on data collected in previous SARS‐CoV‐2 serosurveillance studies, we created a cohort of donors who tested negative for anti‐nucleocapsid (NC) antibodies between August 2022 and September 2023. If these donors donated blood during the follow‐up period, between 1 October 2023 and 12 September 2024, their donation was again tested for anti‐NC to see whether they seroconverted. Results Of the 992 donors whose donation(s) tested negative for anti‐NC between August 2022 and September 2023, 824 (83%) donated during the follow‐up period. Older donors were overrepresented in the study. Of the included donors, 67% seroconverted for anti‐NC after August 2022. Conclusion The majority of Dutch blood donors who were still uninfected acquired primary infection after August 2022, coinciding with the circulation of SARS‐CoV‐2 omicron variants.